interesting interview with Team Fortress 2 lead designer Robin Walker. While the whimsical shooter offers plenty of engaging gameplay, it's most notable accomplishment may be that it serves as a testbed for Valve's future livelihood.
"[When TF2 shipped], MMOs were the dominant story in the industry, and one concern we had was that we might not be able to survive if we didn't build one," Walker told the website.
"We didn't think we were ready to undertake that, but we did think that we might be able to build some pieces of one, learning enough so that if or when we did need to build one, we had less risk on the table. We decided that persistent item design and storage seemed like a reasonable amount of risk for us to bite off, and could be made to fit into TF2's gameplay," Walker explained.